Police said the gang picked up Mostafa Nakib, 45, from his temporary lodge at a shrimp enclosure and shot him dead before slaughtering at a nearby place.

The killers dumped the body in a canal, half-a-kilometre off the scene, from where it was retrieved by police this morning.

Police arrested four persons Ramanimohon, 72, Naren Bepari, 70, Keshab Bepari, 88, and Santosh Mistry, 55, -- in connection with the killing.

"They are being grilled," said Officer-in-Charge of the Sadar Police Station Ishaque Ali.

Relatives of Nakib said he was a victim of politics, but police linked the killing to conflict with his rivals over fish farm.

A case was lodged.